This document defines and discusses focal task specific dystonia (FTSD), also known as occupational dystonia. It begins with an introduction and history of the condition. FTSD is characterized by an involuntary loss of motor control that is triggered by the performance of a specific, often over-practiced task. Common examples include writer's cramp and musician's dystonia. The causes involve both genetic and environmental factors that result in abnormalities in neural inhibition, plasticity, and motor networks in the brain. Treatment options include oral medications, botulinum toxin injections, physical therapy, and in some cases surgery.

1. FOCAL TASK SPECIFIC DYSTONIA
Ade Wijaya, MD – November 2019

2. OUTLINE:
 Introduction
 Definition
 Epidemiology
 Clinical Presentation
 Etiology
 Pathophysiology
 Treatment

3. INTRODUCTION
 In 1830, clerks in the British Civil Service were
noted to develop difficulty with writing. Sir Charles
Bell  Focal Task Spesific Dystonia (FTSD)
 The term “dystonia” was first used in 1911 by
Oppenheim
Oppenheim H (1911) Text-book of nervous diseases for physicians and students. 5th enl. and improved ed. O. Schulze & company, Edinburgh. G. E. Stechert & company, New York.
Bell C (1933) Partial paralyses of the muscles of the extremities’. the nervous system of the human body. Taylor and Francis, London, pp 57–58

4. DEFINITION
“Focal dystonias affecting an isolated body part and
are triggered, at least initially, by a specific action.”
Albanese A et al (2013) Phenomenology and classification of dystonia: a consensus update. Mov Disord 28(7):863–873

5. EPIDEMIOLOGY
Onset in the third to sixth decade
Male > Female
Usually affects the arm, facial muscles or larynx
Overall prevalence: 7 to 69 per million
Defazio G, Berardelli A, Hallett M (2007) Do primary adult-onset focal dystonias share aetiological factors? Brain 130(Pt 5):1183–1193
Epidemiological Study of Dystonia in Europe Collaborative, G (2000) A prevalence study of primary dystonia in eight European countries. J Neurol 247(10):787–792
Butler AG et al (2004) An epidemiologic survey of dystonia within the entire population of northeast England over the past nine years. Adv Neurol 94:95–99

6. CLINICAL PRESENTATION
 Insidious, painless loss of dexterity triggered by
performance of a specific, often over-practiced task
 Symptoms progress over time to trigger
uncontrolled activation of muscle groups, leading to
abnormal postures and movements
 Over time spreads to involve other tasks, or even
spreads to previously unaffected areas of the body
 Sensory tricks, or geste antagonistes, may
temporarily reduce the dystonic symptoms of FTSD
Greene PE, Bressman S (1998) Exteroceptive and interoceptive stimuli in dystonia. Mov Disord 13(3):549–551

7. Writer’s Cramp
Musician’s Hand Dystonia
Embouchure Dystonia

8. ETIOLOGY
Genetic and Environmental
Arylsulfatase G (ARSG) gene
Interhemispheric Inhibition
Possible risk factors include:
• Personality traits, such as perfectionism and anxiety
• Anatomical factors, such as hand size and joint mobility
• Delayed onset of age of musical training
Stahl CM, Frucht SJ. Focal task specific dystonia: a review and update. Journal of neurology. 2017 Jul 1;264(7):1536-41.

9. PATHOPHYSIOLOGY
Decreased short intracortical inhibition (SICI)
impaired surround inhibition, a neural inhibitory mechanism
responsible for the selective recruitment and activation of
muscles necessary for a particular task with inactivation of
the neighboring muscles that are unnecessary
Maladaptive neural plasticity
Abnormal cortical representations of digits and reorganization
of the sensory homunculus in the sensory cortex
Stahl CM, Frucht SJ. Focal task specific dystonia: a review and update. Journal of neurology. 2017 Jul 1;264(7):1536-41.

10. PATHOPHYSIOLOGY
 Network Disorder
Hyperactivation of the basal ganglia
Decreased release of striatal dopamine during hand
activation in patients with writer’s cramp
Cerebellar dysfunction
Stahl CM, Frucht SJ. Focal task specific dystonia: a review and update. Journal of neurology. 2017 Jul 1;264(7):1536-41.

11. TREATMENT
Oral Medications Chemodenervation
Surgery Physical Therapy
Jabusch HC et al (2005) Focal dystonia in musicians: treatment strategies and long-term outcome in 144 patients. Mov Disord 20(12):1623–1626
Jankovic J (2006) Treatment of dystonia. Lancet Neurol 5(10):864–872
Balash Y, Giladi N (2004) Efficacy of pharmacological treatment of dystonia: evidence-based review including meta-analysis of the effect of botulinum toxin and other cure
options. Eur J Neurol 11(6):361–370

12. MEDICATIONS
 Anticholinergic agents like trihexyphenidyl, as well
as other medications, such as primidone, baclofen,
and phenytoin
 Chemodenervation with botulinum toxin type A
Jabusch HC et al (2005) Focal dystonia in musicians: treatment strategies and long-term outcome in 144 patients. Mov Disord 20(12):1623–1626
Jankovic J (2006) Treatment of dystonia. Lancet Neurol 5(10):864–872
Balash Y, Giladi N (2004) Efficacy of pharmacological treatment of dystonia: evidence-based review including meta-analysis of the effect of botulinum toxin and other cure
options. Eur J Neurol 11(6):361–370

13. SUMMARY
 Aberrant motor overactivation during the
performance of a specific, often over-practiced
activity
 Occupational Dystonia
 Genetic and Environmental
 Abnormalities in inhibition, plasticity, and motor
networks

14. THANK YOU